Nuclear warfare beyond counterforce

States with nuclear weapons have improved the survivability of their nuclear weapons and associated delivery systems in case of an adversary attack, even with nuclear weapons. The initial efforts included reinforcing fixed sites to withstand nuclear blasts. These efforts have expanded into creating deeply buried facilities.

Another approach has been to increase the mobility of strategic nuclear delivery systems, thus ensuring that they are challenging to find and target. For example, aircraft capable of delivering nuclear weapons have always been mobile targets that could shift from one airfield to another to reduce the chance of being destroyed. Additionally, land-based ballistic missile launchers are being deployed on either trucks or trains to make them difficult to target.

The sea-launched ballistic missile submarines have combined mobility and hardening; the submarine's strength to withstand water pressure is also effective protection against nuclear blast overpressure and dynamic pressure. Additionally, these submarines operate in the world's largest thermal sink, which reduces their susceptible range to thermal effects. Hence, submarines are not only challenging to find, but they are also highly resistant to nuclear weapon effects should they be detected.

While decreasing their nuclear forces in total numbers, the United States and Russia have steadily increased the percentages of their nuclear forces that are survivable through mobility. Lieber and Press (2017) and Long and Green (2015) contend that improvements in intelligence technology will eventually track and target current mobile delivery methods; however, future sensing capabilities may be rapidly overwhelmed with decoys and other new countermeasures. We also presume that a country initiating a strike would expend their vulnerable weapons and maintain their more survivable weapons in reserve. For this article, we postulate a future where hardening, mobility, deception, and other means will continue to make targeting an adversary's strategic systems increasingly much more difficult.

Nations are also increasing their defences to reduce any adversary's ability to penetrate to their targets. Defences are not new (Cimbala and McDermott 2015). Countries threatened by adversaries attacking with bombers and cruise missiles have established air defence networks. For a while, stealth technology mitigated the advances of air defences; however, the improved sophistication of integrated air defence networks may significantly reduce the ability of bombers and cruise missiles to penetrate to targets. Along with enhanced detection, the range of interceptor missiles has dramatically increased.

Local area defences against ballistic missiles have existed for decades. Recent trends have indicated an increase in the size of the defended area and the effectiveness of the interceptors (Lowther and Cimbala 2017). For example, the Office of the Secretary of Defense (2019) in the 2019 Missile Defense Review states, ‘The United States is protected against a limited ICBM [inter-continental ballistic missile] attack.’

One possible counter to improved defences is faster penetrators, such as hypersonic weapons. A few weapons with such advanced penetrative capabilities may even be able to assist in deterring an attack from a country with an extensive defence network. Zala (2019) concludes the ‘new non-nuclear weapon technologies – such as ballistic missile defense, anti-satellite weapons, and precision-strike missile technology – will make nuclear deterrence relationships that were once somewhat stable less so.’

Proliferation is another challenge to a counterforce strategy (Mazarr 1995; Jo and Gartzke 2007). During the Cold War, the United States and the Soviet Union only had to be concerned about the size of their arsenal relative to their single adversary. Now, each country must also consider its nuclear arsenal relative to all potential nuclear-armed adversaries and coalitions. An extensive exchange between two countries might leave the third country with the most remaining nuclear weapons (Kristensen and Norris 2018).

For this discussion, we postulate a future world where the following holds. Multiple states have nuclear weapons. No state or coalition of states can execute a counterforce first strike that sufficiently eliminates an adversary's nuclear weapons to not be concerned about a nuclear counter-strike in response. No countries have an effective global defence system, rendering all vulnerable to strategic attacks. Each nation needs to consider multiple adversaries. Contrary to our assumptions, Lieber and Press (2017) contend that ‘hardening and concealment—have been undercut by leaps in weapons accuracy and a revolution in remote sensing’ and further ‘countries that have considerable resources can buck these trends and keep their forces survivable, albeit with considerable cost and effort.’ In contrast, Mazarr (2007) states that the United States cannot achieve any of its counterforce goals.

Regarding the relative balance of weapons, we contend that the following nuclear attack scenarios would use one or few nuclear weapons, so these strikes would not considerably change the relative balance of power between the attacking nation, their adversary, and other nuclear-capable nations. However, this greatly complicates the deterrence framework. After expending only a few weapons, the belligerent country retains sufficient weapons to deter a counterforce response. As an alternative response, the attacked country might respond with one or more of the limited strike options being evaluated. However, if the strike and counter-strike cycle proceeds unabated—or worse, escalates—each country will continue to deploy nuclear weapons from their limited arsenal. If this continues, one country will eventually deplete its arsenal of nuclear weapons to the point of not having a viable response. Additionally, either country involved in nuclear exchanges may also become vulnerable to coercion from other nuclear-armed states.

Another consideration in using a nuclear weapon is the range of effects on the adversary, which includes expected fatalities and economic loss. The fallout may also cause fatalities and losses in other countries. Additionally, other countries may be impacted indirectly, such as through loss of critical supplies or inhibited trade.

The leaders should consider the morality of a nuclear attack. The Just War Theory provides four tenets that leaders of a country considering military action should evaluate: (1) the gravity of the threat to their country, (2) alternative means, other than nuclear weapons, to respond, (3) serious prospect of success, and (4) proportionate response to the threat (Martino 1988). United States Catholic bishops promulgate that ‘the indiscriminate and disproportionate nature of nuclear weapons’ cannot achieve this last tenet (Hollerich and Cantu’ 2017). The purpose of a moral response is not retribution but to prevent further harm. If an adversary attacked with their only nuclear weapon, the response should not be a punitive nuclear strike. With nuclear weapons use, the proportionate response is often summarised as the civilian impact, particularly civilian fatalities (Sagan and Weiner 2021). Lonsdale (2019) cites the four Just War tenets in evaluating a country's published nuclear-use policy. Although likely stated differently, world opinion may focus on the same aspects.

Finally, a leader considering nuclear weapons should examine how their adversary or other nations may respond. Political alliances or treaties may compel other countries to respond. If the strike is not counter-force, it will not have diminished the adversary arsenal of nuclear weapons. Will the strike result in an escalating counter-strike? A strike that the attacked country perceives as having extremely inappropriate consequences with regard to the circumstances is probably more likely to result in a significant and possibly more consequential response. For example, in response to a naval blockade, a strike that limits trade routes might escalate less than an attack on a city.

Besides a retaliatory strike or perhaps in combination with a nuclear strike, how else might other countries respond? Could they affect financial and economic assets or impose diplomatic and political costs? In the Cold War, nuclear weapons deterrence was predominately achieved with the threats of retaliatory nuclear strikes.

Countries may try diplomacy to increase the costs towards adversaries who want to use and maintain nuclear weapons and reward the benefits to those who decide not to. Countries that limit or forego nuclear capabilities can receive defense pacts, open trade, and participation in world political forums. In contrast, countries that seek to maintain or even expand nuclear capabilities could face sanctions that include embargos, restricted diplomatic relations, and travel limitations.

This diplomacy aims to penalise powers that seek nuclear capabilities and reward those who don’t, hoping that countries decide not to use nuclear weapons. We want to be clear that the power of nuclear weapons put them in their own category—their use is unlikely to be deterred except by the threat of counter-nuclear strikes. However, other instruments of national power may make the cost too high when combined with counter-nuclear strikes. (Caswel et al. 2011).

The United States Department of Defense (2006) bases its Deterrence Operations Joint Operating Concept on the central idea of influencing another country's decision calculus. The steps to deter a country from undertaking undesirable action may be categorised in four ways. The first is to incentivise restraint, which is avoiding the undesired action. The next is to disincentivise any nuclear action. Encouraging restraint from the undesirable action may be a combination of improving advantages/benefits and reducing disadvantages/costs. In contrast, steps, which include conditional threats, increase the consequences of taking the undesired action and may reduce advantages/benefits along with imposing costs of the undertaking. Table 1 shows the four categories of steps applied to deterring the use of nuclear weapons.

Political, Military, Economic, Social, Information, Infrastructure (PMESII) (Hillson 2009; Lawrence and Murdock 2009; Ducote 2010; Hartley 2015) is an organising construct for evaluating the effects of government and military actions. The PMESII categories provide one approach to identifying advantages and disadvantages. Political benefits may be a favourable treaty or diplomatic relationship, whereas political disadvantages might be restricted diplomatic access. Military advantages include joint training and exercises, and costs may be improved military capabilities of countries threatening countries. Economic benefits are trade agreements or investments with costs being sanctions and other trade restrictions. Social advantages are open travel versus restricted adoptions and immigration. Information advantage is student studies and access to technologies. One possible infrastructure benefit may be investments and developments. The potential benefits and costs are beyond what the military can provide or impose. The whole government can provide greater incentives and disincentives.

How may a country attempt to control escalation? The same logic as the original deterrence, shown in Table 1, applies where the opponent needs to perceive the consequences of an attack, the cost, and benefits and decide not to make any undesired actions. Preventing escalation means the undesired action is a response that has consequences of a larger magnitude. The goal in preventing escalation is to convince the opponent that there are worse options if they respond too aggressively compared to a restrained response or even not responding. A country that executes the first strike hopes to achieve – conducting their strike and deterring a response.

Because of the extensive consequences of deploying a nuclear weapon, deterrence requires significant consequences. Most likely, deterrence will require actions beyond just the military instrument of power. For example, a joint declaration by military and economic allies that they will freeze all financial assets of a country that uses nuclear power against them in any capability would likely contribute to a stronger deterrent. These actions are intended to increase the cost of using nuclear powers to potential aggressors.

We identified and examine a type of target with effects primarily in each of the PMESII categories as alternatives to counterforce targets of the adversary's strategic nuclear systems and national leadership. For example, we examine a demonstration detonation for the political category and an electromagnetic pulse (EMP) in the information category. We examine the six alternatives to the current counterforce strategy, listed in Table 2 in order of the least to most civilian impact.

We examined six types of nuclear weapons uses other than counterforce. Table 3 lists them from left to right in the order of general increasing impact. First, we summarise our conclusions about the deterrence viability of threatening to respond with the same kind of attack. Subsequently, we consider deterring by threatening a more consequential response (a column to the right) and then a less consequential response (a column to the left). Finally, we complete this summary of results by discussing how deterrence options may be made more credible.

In our discussion of each type of nuclear attack, we evaluated whether the threat of responding in kind, meaning the same type of attack, was viable; our conclusions are in the bottom row of Table 3. A country will not be deterred from conducting a nuclear demonstration because of the possibility of their opponent conducting a nuclear demonstration, which has no direct impact on them, in response. A country that is on the losing side of a military conflict and desperate is less likely to be intimidated by the threat of a nuclear strike. The losing side has more to gain by using their nuclear weapons against their enemy's military ground forces. A response with EMP is difficult because it cannot be isolated to the country that first employed an EMP strike. An economic and infrastructure attack is possible; however, it would be highly dependent upon the situation—these types of responses should be investigated. Gallagher and Sorice (2014) argue that threatened responses of targeting population centers may lack enough credibility to provide deterrence. All of these cases present deterrence challenges based on threatening to respond with the same kind of nuclear attack.

In general, threatening to respond with a more severe attack (a column to the right in Table 3) would be more consequential and may be perceived as disproportionate and escalatory. Similarly, a threatened response with a nuclear attack that is less consequential (a column to the left in Table 3) may be perceived as a weak response and not be a sufficient deterrent. After an adversary's destructive attack, a nuclear demonstration would be of no consequence to the adversary and be perceived as a very weak response. Similarly, responding to a nuclear attack on electronic systems, economy, infrastructure, or cities by attacking the aggressor's conventional military forces would not have a considerable impact. Furthermore, striking conventional forces would be difficult without inflicting extensive civilian damage, unless deployed in a combat theatre. The wide impact of EMP does not make it a credible response to achieve nuclear deterrence. However, carefully crafted economic or infrastructure may provide viable responses to ensure deterrence and should be examined.

We contend viable deterrence requires a credible threat. One of our main objectives against various responses to nuclear attacks is that the consequences are disproportionate. Lower yield nuclear weapons provide additional, perhaps more credible, options. For example, low-yield weapons enable striking economic targets with limited casualties. Opponents argue those types of improvements make nuclear weapons more useable. Yet, usability is the heart of the deterrence's threatened harm. Too large of yield may not be viable and limit a country's ability to respond and hence deter in the first place.

Additionally, the quantity of nuclear weapons affects deterrence. Rauchhaus (2009) found that when both sides have symmetry in a nuclear weapons capability, there is significantly less chance of war. Modern deterrence requires sufficient weapons to execute a response and needs to have enough weapons to continue to deter the employment of nuclear weapons.